Elastomeric compositions and their use in articles

ABSTRACT

A dynamically vulcanized alloy contains at least one isobutylene-containing elastomer, at least one thermoplastic resin, and an anhydride functionalized oligomer grafted to the thermoplastic resin. In the alloy, the elastomer is present as a dispersed phase of small vulcanized or partially vulcanized particles in a continuous phase of the thermoplastic resin and the alloy is substantially absent of any sulfonamides.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Ser. No. 14/356,339, filedMay 5, 2014, now allowed, which is a National Stage application ofInternational Application No. PCT/US2012/064645, filed Nov. 12, 2012 andclaimed the benefit thereof, and wherein the International applicationclaimed the benefit of prior U.S. Application Ser. No. 61/577,409, filedDec. 19, 2011, the disclosures of which are incorporated herein byreference in their entirety.

FIELD OF THE INVENTION

The present invention relates to thermoplastic elastomeric compositions.More particularly, the present invention is directed to a thermoplasticelastomeric composition comprising compounds that act as both anextender and reactive plasticizer for the thermoplastic in thecomposition.

BACKGROUND OF THE INVENTION

The present invention is related to thermoplastic elastomericcompositions particularly useful for tire and other industrial rubberapplications, reinforced or otherwise, that require impermeabilitycharacteristics.

EP 0 722 850 B1 discloses a low-permeability thermoplastic elastomericcomposition that is excellent as an innerliner in pneumatic tires. Thiscomposition comprises a low permeability thermoplastic in which isdispersed a low permeability rubber. EP 0 969 039 A1 discloses a similarcomposition and teaches that the small particle size rubber dispersed inthe thermoplastic was important to achieve acceptable durability of theresulting composition.

There are also examples of the use of a thermoplastic elastomer composedof a rubber and a thermoplastic for use as an innerliner in a tire. But,in general, a flexible material of the type disclosed therein has lowheat resistance. When the thermoplastic material in the composition hasa melting point less than the tire vulcanization temperature, when thetire curing bladder is released at the end of the curing cycle, theinside surface of the tire may have defects due to the thermoplasticmaterial of the composition sticking to rubber of the curing bladder.

Controlling the viscosity difference between the two different materialsin the composition is also considered important, as the viscositydifference affects the dispersed rubber particle size. To obtain thedesired viscosity reduction, it is known to add a plasticizer to thecomposition. The most common plasticizer used is butylbenzylsulfonamide(BBSA). However, when using BBSA as the plasticizer, the BBSA is notbound or grafted to the thermoplastic resin in the composition and theunbound BBSA is known to volatize out during subsequent heating anddownstream processing of the thermoplastic elastomer. Suchvolatilization of the BBSA can result in undesirable blemishes on theproduct surface, this is also known as ‘blooming’ and while notdetrimental to the performance of the product, does result in anunsatisfactory appearance and an impression of a faulty product.Additionally, it is desired to reduce the amount of volatiles that arereleased into the atmosphere during downstream operations using thethermoplastic elastomer.

To that end, the inventors have previously sought to reduce the amountof BBSA used as a plasticizer in the thermoplastic elastomercompositions. The resulting compositions had lower BBSA volatile organiccompounds and surprisingly good fluidity. The melting point of the newcompositions was also higher, which is a desirable attribute. Nopenalties in engineering properties were incurred. However, attempts tofully eliminate the BBSA from the elastomer-rich compositions, until thepresent invention, were unsuccessful as the elastomer component of thecomposition failed to achieve the desired phase inversion and did notconvert to a dispersed phase in a thermoplastic resin domain and theresulting composition was too soft. To achieve the desired phaseinversion, a small level of BBSA, approximately 2.5 wt % based on thetotal weight of the composition, had to be present in the compositionduring composition mixing. The present invention is directed toaddressing the desire to continue to reduce, and preferably eliminateBBSA, and in particular unbound sulfonamides, in the composition.

SUMMARY OF THE INVENTION

The present invention is directed to a thermoplastic elastomericcomposition having improved characteristics over previously knownsimilar compositions.

The present invention is directed to a dynamically vulcanized alloycontaining at least one isobutylene-containing elastomer, at least onethermoplastic resin, and an anhydride functionalized oligomer grafted tothe thermoplastic resin. In the alloy, the elastomer is present as adispersed phase of small vulcanized or partially vulcanized particles ina continuous phase of the thermoplastic resin and the alloy issubstantially absent of any sulfonamides.

In the invention, the oligomer may be selected from the group consistingof an alkyl, an aryl, and an alkenyl oligomer. The oligomer preferablyhas a molecular weight in the range of 500 to 2500.

In the invention, the anhydride functionalized oligomer is present inthe alloy in an amount in the range of 2 to 30 phr, based on the amountof the isobutylene-containing elastomer in the alloy.

Also disclosed and useful in any embodiment of the present invention,the thermoplastic resin has a relative viscosity of not more than 3.9.The alloy may contain a mixture of thermoplastic resins, wherein therelative viscosities of the different thermoplastic resins aredifferent, but wherein the relative viscosity of the mixture is not morethan 3.9. Preferably, the relative viscosity of the thermoplastic resin,either as a single component or a mixture of resin, is not less than2.0. Thermoplastic resins useful in any embodiment may be copolymers orhomopolymers.

Also disclosed herein and useful in any embodiment of the presentinvention, the elastomer may be a halogenated butyl rubber or a polymerof isobutylene derived units and alkylstyrene derived units. The polymerof isobutylene derived units and alkylstyrene, preferablyparamethylstyrene, derived units may be halogenated. In any embodiment,when the elastomer is a polymer of isobutylene derived units andalkylstyrene, the polymer comprises 7 to 12 wt % of alkylstyrene,preferably paramethylstyrene. In any embodiment, the elastomer maycontain 1.0 to 1.5 mol % of a halogen; the halogen may be bromine orchlorine.

Also disclosed herein and useful in any embodiment of the presentinvention, the alloy is an elastomer-rich compound, wherein theelastomer is present in the alloy in an amount in the range of 55 to 90weight percent. For such elastomer-rich compounds, the presence of theanhydride functionalized oligomer that is grafted to the thermoplasticresin works to effectively increase the amount of thermoplastic presentin the alloy and enables the more dominate compound in the alloy, i.e.the elastomer, to achieve phase conversion whereby the elastomer ispresent in a discrete phase within a continuous phase of thermoplasticresin.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described by way of example and with reference tothe accompanying drawing in which:

FIG. 1 is a graph showing the viscosity versus shear for binary blendsof polyamides and AFOs, and

FIG. 2 is a graph showing the elastic MDR torque vs. cure times ofdisclosed compounds at an elevated temperature of 240° C.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to thermoplastic elastomer compositionthat has the elastomer present in the composition as discreet domains ina thermoplastic resin matrix wherein to achieve the desired morphology,a combination of anhydrides such as polyisobutylene succinic anhydrideand at least one medium viscosity thermoplastic resin, preferablypolyamide, is present in the composition. This combination of additivesin the composition enables the elimination of sulfonamide containingplasticizers in the thermoplastic elastomer; that is the composition issubstantially free of sulfonamides wherein ‘substantially free’ isdefined as less than 100 ppm by weight of the sulfonamide. Inparticular, the elimination of BBSA from the composition while stillachieving the desired morphology. Additionally, in order to achieve thebest balance of key performance properties; namely impermeability andlow temperature fatigue we found it is preferable to use an elastomerderived from a defined amount of styrene components and optionally, witha defined halogen content.

Various specific embodiments, versions, and examples of the inventionwill now be described, including preferred embodiments and definitionsthat are adopted herein for purposes of understanding the claimedinvention. While the illustrative embodiments have been described withparticularity, it will be understood that various other modificationswill be apparent to and can be readily made by those skilled in the artwithout departing from the spirit and scope of the invention. Fordetermining infringement, the scope of the “invention” will refer to anyone or more of the appended claims, including their equivalents andelements or limitations that are equivalent to those that are recited.

DEFINITIONS

Definitions applicable to the presently described invention are asdescribed below.

Polymer may be used to refer to homopolymers, copolymers, interpolymers,terpolymers, etc. Likewise, a copolymer may refer to a polymercomprising at least two monomers, optionally with other monomers. When apolymer is referred to as comprising a monomer, the monomer is presentin the polymer in the polymerized form of the monomer or in thepolymerized form of a derivative from the monomer (i.e., a monomericunit). However, for ease of reference the phrase comprising the(respective) monomer or the like is used as shorthand. Likewise, whencatalyst components are described as comprising neutral stable forms ofthe components, it is well understood by one skilled in the art, thatthe ionic form of the component is the form that reacts with themonomers to produce polymers.

Elastomer refers to any polymer or composition of polymers consistentwith the ASTM D1566 definition: “a material that is capable ofrecovering from large deformations, and can be, or already is, modifiedto a state in which it is essentially insoluble, if vulcanized, (but canswell) in a solvent.” Elastomers are often also referred to as rubbers;the term elastomer may be used herein interchangeably with the termrubber.

The term “phr” is parts per hundred rubber or “parts”, and is a measurecommon in the art wherein components of a composition are measuredrelative to a total of all of the elastomer components. The total phr orparts for all rubber components, whether one, two, three, or moredifferent rubber components is present in a given recipe is normallydefined as 100 phr. All other non-rubber components are ratioed againstthe 100 parts of rubber and are expressed in phr. This way one caneasily compare, for example, the levels of curatives or filler loadings,etc., between different compositions based on the same relativeproportion of rubber without the need to recalculate percentages forevery component after adjusting levels of only one, or more,component(s).

Isoolefin refers to any olefin monomer having at least one carbon havingtwo substitutions on that carbon. Multiolefin refers to any monomerhaving two or more double bonds. In a preferred embodiment, themultiolefin is any monomer comprising two conjugated double bonds suchas a conjugated diene like isoprene.

Isobutylene based elastomer or polymer refers to elastomers or polymerscomprising at least 70 mol % repeat units from isobutylene.

Elastomer

Useful elastomeric compositions for this invention include elastomersderived from a mixture of monomers, the mixture having at least (1) a C₄to C₇ isoolefin monomer component with (2) a multiolefin, monomercomponent. The isoolefin is present in a range from 70 to 99.5 wt % byweight of the total monomers in any embodiment, or 85 to 99.5 wt % inany embodiment. The multiolefin derived component is present in amountsin the range of from 30 to about 0.5 wt % in any embodiment, or from 15to 0.5 wt % in any embodiment, or from 8 to 0.5 wt % in any embodiment.

The isoolefin is a C₄ to C₇ compound, non-limiting examples of which arecompounds such as isobutylene, isobutene, 2-methyl-1-butene,3-methyl-1-butene, 2-methyl-2-butene, 1-butene, 2-butene, methyl vinylether, indene, vinyltrimethylsilane, hexene, and 4-methyl-1-pentene. Themultiolefin is a C₄ to C₁₄ multiolefin such as isoprene, butadiene,2,3-dimethyl-1,3-butadiene, myrcene, 6,6-dimethyl-fulvene, hexadiene,cyclopentadiene, and piperylene. Other polymerizable monomers such asstyrene and dichlorostyrene are also suitable for homopolymerization orcopolymerization in butyl rubbers.

Preferred elastomers useful in the practice of this invention includeisobutylene-based copolymers. As stated above, an isobutylene basedelastomer or a polymer refers to an elastomer or a polymer comprising atleast 70 mol % repeat units from isobutylene and at least one otherpolymerizable unit. The isobutylene-based copolymer may or may not behalogenated.

In any embodiment of the invention, the elastomer may be a butyl-typerubber or branched butyl-type rubber, especially halogenated versions ofthese elastomers. Useful elastomers are unsaturated butyl rubbers suchcopolymers of olefins or isoolefins and multiolefins. Non-limitingexamples of unsaturated elastomers useful in the method and compositionof the present invention are poly(isobutylene-co-isoprene),polyisoprene, polybutadiene, polyisobutylene,poly(styrene-co-butadiene), natural rubber, star-branched butyl rubber,and mixtures thereof. Useful elastomers in the present invention can bemade by any suitable means known in the art, and the invention is notherein limited by the method of producing the elastomer. The butylrubber polymer of the invention is obtained by reacting isobutylene with0.5 to 8 wt % isoprene, or reacting isobutylene with 0.5 wt % to 5.0 wt% isoprene—the remaining weight percent of the polymer being derivedfrom isobutylene.

Elastomeric compositions of the present invention may also comprise atleast one random copolymer comprising a C₄ to C₇ isoolefin and analkylstyrene comonomer. The isoolefin may be selected from any of theabove listed C₄ to C₇ isoolefin monomers, and is preferably anisomonoolefin, and in any embodiment may be isobutylene. Thealkylstyrene may be para-methylstyrene, containing at least 80%, morealternatively at least 90% by weight of the para-isomer. The randomcopolymer may optionally include functionalized interpolymers. Thefunctionalized interpolymers have at least one or more of the alkylsubstituents groups present in the styrene monomer units; thesubstituent group may be a benzylic halogen or some other functionalgroup. In any embodiment, the polymer may be a random elastomericcopolymer of a C₄ to C₆ α-olefin and an alkylstyrene comonomer. Thealkylstyrene comonomer may be para-methylstyrene containing at least80%, alternatively at least 90% by weight, of the para-isomer. Therandom comonomer may optionally include functionalized interpolymerswherein at least one or more of the alkyl substituents groups present inthe styrene monomer units contain benzylic halogen or some otherfunctional group. Exemplary materials of any embodiment may becharacterized as polymers containing the following monomer unitsrandomly spaced along the polymer chain:

wherein R and R¹ are independently hydrogen, lower alkyl, such as a C₁to C₇ alkyl and primary or secondary alkyl halides and X is a functionalgroup such as halogen. In an embodiment, R and R¹ are each hydrogen. Upto 60 mol % of the para-substituted styrene present in the randompolymer structure may be the functionalized structure (2) above in anyembodiment. Alternatively, in any embodiment, from 0.1 to 5 mol % or 0.2to 3 mol % of the para-substituted styrene present may be thefunctionalized structure (2) above.

The functional group X may be halogen or some other functional groupwhich may be incorporated by nucleophilic substitution of any benzylichalogen with other groups such as carboxylic acids; carboxy salts;carboxy esters, amides and imides; hydroxy; alkoxide; phenoxide;thiolate; thioether; xanthate; cyanide; cyanate; amino and mixturesthereof. These functionalized isomonoolefin copolymers, their method ofpreparation, methods of functionalization, and cure are moreparticularly disclosed in U.S. Pat. No. 5,162,445.

In any embodiment, the elastomer comprises random polymers ofisobutylene and 0.5 to 20 mol % para-methylstyrene wherein up to 60 mol% of the methyl substituent groups present on the benzyl ring isfunctionalized with a halogen such a bromine or chlorine, an acid, or anester.

In any embodiment, the functionality is selected such that it can reactor form polar bonds with functional groups present in the matrixpolymer, for example, acid, amino or hydroxyl functional groups, whenthe polymer components are mixed at high temperatures.

Brominated poly(isobutylene-co-p-methylstyrene) “BIMSM” polymers usefulin the present invention generally contain from 0.1 to 5 mol % ofbromomethylstyrene groups relative to the total amount of monomerderived units in the copolymer. In any embodiment of the invention usingBIMSM, the amount of bromomethyl groups is from 0.5 to 3.0 mol %, orfrom 0.3 to 2.8 mol %, or from 0.4 to 2.5 mol %, or from 0.5 to 2.0 mol%, wherein a desirable range for the present invention may be anycombination of any upper limit with any lower limit. Also in accordancewith the invention, the BIMSM polymer has either 1.0 to 2.0 mol %bromomethyl groups, or 1.0 to 1.5 mol % of bromomethyl groups. Expressedanother way, exemplary BIMSM polymers useful in the present inventioncontain from 0.2 to 10 wt % of bromine, based on the weight of thepolymer, or from 0.4 to 6 wt % bromine, or from 0.6 to 5.6 wt %. UsefulBIMSM polymers may be substantially free of ring halogen or halogen inthe polymer backbone chain. In any embodiment, the random polymer is apolymer of C₄ to C₇ isoolefin derived units (or isomonoolefin),para-methylstyrene derived units and para-(halomethylstyrene) derivedunits, wherein the para-(halomethylstyrene) units are present in thepolymer from 0.5 to 2.0 mol % based on the total number ofpara-methylstyrene, and wherein the para-methylstyrene derived units arepresent from 5 to 15 wt %, or 7 to 12 wt %, based on the total weight ofthe polymer. In any embodiment, the para-(halomethylstyrene) ispara-(bromomethylstyrene).

Thermoplastic Resin

For purposes of the present invention, a thermoplastic (alternativelyreferred to as thermoplastic resin) is a thermoplastic polymer,copolymer, or mixture thereof having a Young's modulus of more than 200MPa at 23° C. The resin should have a melting temperature of about 170°C. to about 260° C., preferably less than 260° C., and most preferablyless than about 240° C. By conventional definition, a thermoplastic is asynthetic resin that softens when heat is applied and regains itsoriginal properties upon cooling.

Such thermoplastic resins may be used singly or in combination andgenerally contain nitrogen, oxygen, halogen, sulfur or other groupscapable of interacting with an aromatic functional groups such ashalogen or acidic groups. Suitable thermoplastic resins include resinsselected from the group consisting or polyamides, polyimides,polycarbonates, polyesters, polysulfones, polylactones, polyacetals,acrylonitrile-butadiene-styrene resins (ABS), polyphenyleneoxide (PPO),polyphenylene sulfide (PPS), polystyrene, styrene-acrylonitrile resins(SAN), styrene maleic anhydride resins (SMA), aromatic polyketones(PEEK, PED, and PEKK), ethylene copolymer resins (EVA or EVOH) andmixtures thereof.

Suitable polyamides (nylons) comprise crystalline or resinous, highmolecular weight solid polymers including copolymers and terpolymershaving recurring amide units within the polymer chain. Polyamides may beprepared by polymerization of one or more epsilon lactams such ascaprolactam, pyrrolidione, lauryllactam and aminoundecanoic lactam, oramino acid, or by condensation of dibasic acids and diamines Bothfiber-forming and molding grade nylons are suitable. Examples of suchpolyamides are polycaprolactam (nylon-6), polylauryllactam (nylon-12),polyhexamethyleneadipamide (nylon-6,6) polyhexamethyleneazelamide(nylon-6,9), polyhexamethylenesebacamide (nylon-6,10),polyhexamethyleneisophthalamide (nylon-6, IP) and the condensationproduct of 11-aminoundecanoic acid (nylon-11). Commercially availablepolyamides may be advantageously used in the practice of this invention,with linear crystalline polyamides having a softening point or meltingpoint between 160 and 260° C. being preferred.

Suitable polyesters which may be employed include the polymer reactionproducts of one or a mixture of aliphatic or aromatic polycarboxylicacids esters of anhydrides and one or a mixture of diols. Examples ofsatisfactory polyesters include poly(trans-1,4-cyclohexylene C₂₋₆ alkanedicarboxylates such as poly(trans-1,4-cyclohexylene succinate) andpoly(trans-1,4-cyclohexylene adipate); poly(cis ortrans-1,4-cyclohexanedimethylene)alkanedicarboxylates such aspoly(cis-1,4-cyclohexanedimethylene)oxlate andpoly-(cis-1,4-cyclohexanedimethylene) succinate, poly(C₂₋₄ alkyleneterephthalates) such as polyethyleneterephthalate andpolytetramethylene-terephthalate, poly(C₂₋₄ alkylene isophthalates suchas polyethyleneisophthalate and polytetramethylene-isophthalate and likematerials. Preferred polyesters are derived from aromatic dicarboxylicacids such as naphthalenic or phthalic acids and C₂ to C₄ diols, such aspolyethylene terephthalate and polybutylene terephthalate. Preferredpolyesters will have a melting point in the range of 160° C. to 260° C.

Poly(phenylene ether) (PPE) resins which may be used in accordance withthis invention are well known, commercially available materials producedby the oxidative coupling polymerization of alkyl substituted phenols.They are generally linear, amorphous polymers having a glass transitiontemperature in the range of 190° C. to 235° C.

Ethylene copolymer resins useful in the invention include copolymers ofethylene with unsaturated esters of lower carboxylic acids as well asthe carboxylic acids per se. In particular, copolymers of ethylene withvinylacetate or alkyl acrylates for example methyl acrylate and ethylacrylate can be employed. These ethylene copolymers typically compriseabout 60 to about 99 wt % ethylene, preferably about 70 to 95 wt %ethylene, more preferably about 75 to about 90 wt % ethylene. Theexpression “ethylene copolymer resin” as used herein means, generally,copolymers of ethylene with unsaturated esters of lower (C₁-C₄)monocarboxylic acids and the acids themselves; e.g. acrylic acid, vinylesters or alkyl acrylates. It is also meant to include both “EVA” and“EVOH”, which refer to ethylene-vinylacetate copolymers, and theirhydrolyzed counterpart ethylene-vinyl alcohols.

Thermoplastic Elastomeric Composition

At least one of any of the above elastomers and at least one of any ofthe above thermoplastics are blended to form a dynamically vulcanizedalloy. The term “dynamic vulcanization” is used herein to connote avulcanization process in which the vulcanizable elastomer is vulcanizedin the presence of a thermoplastic under conditions of high shear andelevated temperature. As a result, the vulcanizable elastomer issimultaneously crosslinked and preferably becomes dispersed as fine submicron size particles of a “micro gel” within the thermoplastic. Theresulting material is often referred to as a dynamically vulcanizedalloy (“DVA”).

Dynamic vulcanization is effected by mixing the ingredients at atemperature which is at or above the curing temperature of theelastomer, and also above the melt temperature of the thermoplasticcomponent, in equipment such as roll mills, Banbury™ mixers, continuousmixers, kneaders or mixing extruders, e.g., Buss kneaders, twin ormultiple screw extruders. The unique characteristic of the dynamicallycured compositions is that, notwithstanding the fact that the elastomercomponent may be fully cured, the compositions can be processed andreprocessed by conventional thermoplastic processing techniques such asfilm blowing, extrusion, injection molding, compression molding, etc.Scrap or flashing can also be salvaged and reprocessed; those skilled inthe art will appreciate that conventional elastomeric thermoset scrap,comprising only elastomer polymers, cannot readily be reprocessed due tothe cross-linking characteristics of the vulcanized polymer.

Preferably the thermoplastic resin may be present in an amount rangingfrom about 10 to 98 wt %, preferably from about 20 to 95 wt %, theelastomer may be present in an amount ranging from about 2 to 90 wt %,preferably from about 5 to 80 wt %, based on the polymer blend. Forelastomeric-rich blends, the amount of thermoplastic resin in thepolymer blend is in the range of 45 to 10 wt %, and the elastomer ispresent in the amount of 90 to 55 wt %.

The elastomer may be present in the composition in a range up to 90 wt %in any embodiment, or up to 80 wt % in any embodiment, or up to 70 wt %in any embodiment. In the invention, the elastomer may be present fromat least 2 wt %, and from at least 5 wt % in another embodiment, andfrom at least 5 wt % in yet another embodiment, and from at least 10 wt% in yet another embodiment. A desirable embodiment may include anycombination of any upper wt % limit and any lower wt % limit.

In preparing the DVA, other materials may be blended with either theelastomer or the thermoplastic, before the elastomer and thethermoplastic are combined in the blender or added to the mixer duringor after the thermoplastic and elastomer have already been introduced toeach other. These other materials may be added to assist withpreparation of the DVA or to provide desired physical properties to theDVA. Such additional materials include, but are not limited to,curatives, compatibilizers, extenders and polyamide oligomers or lowmolecular weight polyamide and other lubricants as described in U.S.Pat. No. 8,021,730 B2 which is incorporated by reference.

With reference to the elastomers of the disclosed invention,“vulcanized” or “cured” refers to the chemical reaction that forms bondsor cross-links between the polymer chains of the elastomer. Curing ofthe elastomer is generally accomplished by the incorporation of thecuring agents and/or accelerators, with the overall mixture of suchagents referred to as the cure system or cure package.

Suitable curing components include sulfur, metal oxides, organometalliccompounds, radical initiators. Common curatives include ZnO, CaO, MgO,Al2O3, CrO3, FeO, Fe2O3, and NiO. These metal oxides can be used aloneor in conjunction with metal stearate complexes (e.g., the stearatesalts of Zn, Ca, Mg, and Al), or with stearic acid or other organicacids and either a sulfur compound or an alkyl or aryl peroxide compoundor diazo free radical initiators. If peroxides are used, peroxideco-agent commonly used in the art may be employed. The use of peroxidecurative may be avoided if the thermoplastic resin is one such that thepresence of peroxide would cause the thermoplastic resin to cross-link.

As noted, accelerants (also known as accelerators) may be added with thecurative to form a cure package. Suitable curative accelerators includeamines, guanidines, thioureas, thiazoles, thiurams, sulfenamides,sulfenimides, thiocarbamates, xanthates, and the like. Numerousaccelerators are known in the art and include, but are not limited to,the following: stearic acid, diphenyl guanidine (DPG),tetramethylthiuram disulfide (TMTD), 4,4′-dithiodimorpholine (DTDM),tetrabutylthiuram disulfide (TBTD), 2,2′-benzothiazyl disulfide (MBTS),hexamethylene-1,6-bisthiosulfate disodium salt dihydrate,2-(morpholinothio)benzothiazole (MBS or MOR), compositions of 90% MORand 10% MBTS (MOR90), N-tertiarybutyl-2-benzothiazole sulfenamide(TBBS), and N-oxydiethylene thiocarbamyl-N-oxydiethylene sulfonamide(OTOS), zinc 2-ethyl hexanoate (ZEH), N,N′-diethyl thiourea.

In any embodiment of the invention, at least one curing agent istypically present at about 0.1 to about 15 phr; alternatively at about1.0 to about 10 phr, or at about 1.0 to 3.0 phr, or at about 1.0 to 2.5phr. If only a single curing agent is used, it is preferably a metaloxide such as zinc oxide.

In an embodiment of the DVA, due to the goal of the elastomer beingpresent as discrete particles in a thermoplastic domain, the addition ofthe curing components and the temperature profile of the components areadjusted to ensure the correct morphology is developed. Thus, if thereare multiple mixing stages in the preparation of the DVA, the curativesmay be added during an earlier stage wherein the elastomer alone isbeing prepared. Alternatively, the curatives may be added just beforethe elastomer and thermoplastic resin are combined or even after thethermoplastic has melted and been mixed with the rubber. Sub-inclusionsof the thermoplastic inside the rubber particles may also be present.Although discrete rubber particle morphology in a continuousthermoplastic matrix is the preferred morphology, the invention is notlimited to only this morphology and may also include morphologies whereboth the elastomer and the thermoplastic are continuous. But for anysub-inclusions in the elastomer, the thermoplastic resin will preferablynot be discontinuous in the DVA.

Minimizing the viscosity differential between the elastomer and thethermoplastic resin components during mixing and/or processing enhancesuniform mixing and fine blend morphology that significantly enhance goodblend mechanical as well as desired permeability properties. However, asa consequence of the flow activation and shear thinning characteristicinherent in elastomeric polymers, reduced viscosity values of theelastomeric polymers at the elevated temperatures and shear ratesencountered during mixing are much more pronounced than the reductionsin viscosity of the thermoplastic component with which the elastomer isblended. It is desired to reduce this viscosity difference between thematerials to achieve a DVA with acceptable elastomeric dispersion sizes.

Components previously used to compatibilize the viscosity between theelastomer and thermoplastic components include low molecular weightpolyamides, maleic anhydride grafted polymers having a molecular weighton the order of 10,000 or greater, methacrylate copolymers, tertiaryamines and secondary diamines One common group of compatibilizers aremaleic anhydride-grafted ethylene-ethyl acrylate copolymers (a solidrubbery material available from Mitsui-DuPont as AR-201 having a meltflow rate of 7 g/10 min measured per JIS K6710). These compounds may actto increase the ‘effective’ amount of thermoplastic material in theelastomeric/thermoplastic compound. The amount of additive is selectedto achieve the desired viscosity comparison without negatively affectingthe characteristics of the DVA. If too much is present, impermeabilitymay be decreased and the excess may have to be removed duringpost-processing. If not enough compatibilizer is present, the elastomermay not invert phases to become the dispersed phase in the thermoplasticresin matrix.

Compounds commonly referred to as plasticizers have also typically beenemployed as compatibilizers. As already discussed, it has beenconventional in the art to use a sulfonamide, such as BBSA, as theplasticizer in the DVA. The presence of the sulfonamide has, until thepresent invention, been felt to be a necessary component in thecomposition despite any negative ‘blooming’ onto the final product thatmight occur.

In the present invention, Applicants have determined that the desiredcompatibility between the elastomer and thermoplastic resin may beobtained in the absence of any sulfonamides in the material, and whereinthe desired properties of the DVA, in particular improved impermeabilitywith good morphology, can be achieved by the selective use of a mediumrelative viscosity nylon or blends of high and medium relative viscositynylons and/or low relatively viscosity nylons in combination with a lowmolecular weight anhydride functionalized oligomer (AFO). For optimumbalance of durability versus processability it is desirable to minimizeor even eliminate the low molecular weight nylon, i.e. those having a MWof less than 10,000. In the invention, low molecular weight nylon ispresent in the composition in an amount of 0 to 5 wt % of the totalcomposition, preferably 0 to 3 wt %, more preferably 0 wt % of the totalcomposition; expressed alternatively, the amount of low molecular weightnylon in the invention is 0 to 10 wt %, preferably 0 to 5 wt %, morepreferably 0 wt %, of the total ‘effective amount’ of thermoplasticcomponents in the compound.

The terminology of high, medium and low viscosity nylon is defined interms of relative viscosity, calculated per ASTM D2857 and is the ratioof the viscosity of the solution to the viscosity of the solvent inwhich the polymer is dissolved, as specified in exemplary polyamides rawmaterial useful for this invention and shown in Table 1 below.

TABLE 1 Polyamide Comonomer Ratio Relative Viscosity (1% ViscosityGrades PA6/PA66, % in 96% H₂SO₄ at 23° C.) Classification CommercialSource PA 6/66 85/15 4.1 High UBE 5033B PA 6/66 80/20 3.4 Medium UBE5024B PA 6/66 85/15 2.5 Low UBE 5013B PA 6/66 85/15 2.3 Low Novamid 2010PA 6/66 80/20 3.3 Intermediate Ultramid C33 01 PA 6/66 80/20 3.1Intermediate Ultramid C31 01 PA 6 100/0  2.7 Low Ultramid B27 PA 6100/0  2.5 to 2.74 Low Ultramid B26 HM 01When the relative viscosity is at or above 4.0, the resin has a relativeviscosity classification of high. When the relative viscosity is in therange of 3.4 to 3.9, the resin has a relative viscosity classificationof medium. When the relative viscosity is in the range of 2.9 to 3.3,the resin has a relative viscosity classification of intermediate andmay also be classified as medium or low. For resin having a relativeviscosity below 2.9, the resin has a relative viscosity classificationof low, with those below 2.0 being classified as ultra low.

In any embodiment of the present invention, a thermoplastic copolymer orhomopolymer having a relative viscosity lower than the primarythermoplastic component is used to aid in reduction of the viscosity ofthe thermoplastic during mixing of the DVA. When added, the amount ofrelatively lower viscosity thermoplastic is in the range of 5 to 25percent of the total thermoplastic resin present in the composition.This results in a thermoplastic viscosity that is relatively low incomparison to the viscosity of the elastomer during mixing and/orprocessing. For high relative viscosity (RV) grades of thermoplasticresin, the thermoplastic resin may require a greater amount ofcompatibilizers in the alloy. Whether the thermoplastic component of theDVA is a single medium relative viscosity thermoplastic resin or amixture of two or more thermoplastic resins, the thermoplastic resin,preferably polyamide, should have a relative viscosity in the range inthe range of 3.9 to 2.9, preferably in the range of 3.5 to 2.9.

In accordance with the present invention, to obtain the correctmorphology in elastomer-rich compositions, i.e. greater than 55 wt %elastomer in the composition, the viscosity of the thermoplastic plusthe AFO should be lower than the viscosity of the elastomer. Anhydridemoieties, both maleic and succinic anhydride moities, have an affinityand compatibility with the thermoplastics employed in the compositionsof this invention. The anhydrides are miscible or sufficientlycompatible with the thermoplastic, and, not wishing to be bound by anytheory, it is believed that the anhydrides may also act as scavengersfor any terminal amines in the thermoplastic, causing the anhydride tograft to the thermoplastic. As the AFO grafts with the thermoplasticresin during mixing of the DVA, the AFO is added into the mixer/extrudersimultaneously with the thermoplastic resin or as the thermoplasticresin begins to melt in the mixer/extruder; if the AFO is added prior tothe inclusion of the thermoplastic resin, the oligomer is simply mixedwith the elastomer and does not react with the elastomer. As a result ofthe grafting reaction, the anhydride functionalized oligomer is fixedwithin the DVA, and does not volatize out like conventionalplasticizers/compatibilizers during post DVA processing operations suchas film blowing or tire curing. Thus, the resulting DVA has a lowvolatile organic compound emissions. This is believed to be mostapplicable when using polar thermoplastics. Furthermore, it wassurprisingly found that the melting point of a polyamide thermoplasticphase is invariant when the anhydrides are used, contrary to traditionalplasticizers for polyamide thermoplastics such as n-butyl benzenesulfonamides that negatively depress the melting point of thethermoplastic.

Both maleic and succinic anhydrides functionalized oligomers are usefulin the present invention. The anhydride functionalized oligomer may beprepared by thermal or chloro methods known in the art of reacting analkyl, aryl, or olefin oligomer with anhydride, preferably maleicanhydride. The oligomer of any embodiment of the invention, includingcopolymers of lower olefins, being reacted with the anhydride, has amolecular weight in the range of about 500 to 5000, or 500 to 2500, or750 to 2500, or 500 to 1500. The oligomer of the invention may also havea molecular weight in the ranges of 1000 to 5000, 800 to 2500, or 750 to1250. Specific examples of succinic anhydrides include poly-isobutylenesuccinic anhydride, poly-butene succinic anhydride, n-octenyl succinicanhydride, n-hexenyl succinic anhydride, and dodocenyl succinicanhydride.

The most preferred anhydride functionalized oligomers for this inventionare those derived from polyisobutene and are commonly known aspolyisobutylene succinic anhydride or polyisobutene succinic anhydride(PIBSA). The PIBSA may be made by cationic polymerization of isobutenewith boron trifluoride as catalyst. In the course of the polymerization,high concentations of α-olefins are formed during the transfer reactionand as a result the polymerization product has a high proportion ofterminal double bonds (α-olefin). They are normally clear to amberviscous liquids and are specially optimized during the postpolymerization maleitation reaction to have a low bismaleination.

The anhydride level of the AFO of the invention may vary and a preferredrange is a few percent up to about 30 wt % with a preferred range of 5to 25 wt % and a more preferred range of 7 to 17 wt % and a mostpreferred range of 9 to 15 wt %.

The impact on the viscosity of a thermoplastic resin by the inclusion ofan AFO was studied. Binary blends of polyamide copolymer and PIBSA wereblended in a twin screw extruder having an L/D ratio of 7.5/1.5 andwherein the temperature in the extruder were sufficient to melt thethermoplastic resin. The amount of PIBSA was varied. These results areset forth in Table 2 below.

TABLE 2 Blend 1 Blend 2 Blend 3 Blend 4 Polyamide copolymer 1*, % 100 9590 87 84 PIBSA*, % — 5 10 13 16 PIBSA, as parts per 70 phr — 3.7 7.510.0 13.3 polyamide copolymer Test Results LCR (Pa · s) @300 (1/sec) 817926 622 241 157 @ 200° C. (L/D 7.5/1.5) LCR (Pa · s) @300 (1/sec) — 12631083 953 709 @ 200° C. (L/D 30/1) MOCON at 60° C. 0.012 0.015 0.016 — —Melt Temp, ° C. 193 191 191 192 192 *see Table 4 below for materialidentification

Shear rates and shear viscosities were also tested for the binaryblends. The results are set forth in FIG. 1. The use of only 5 wt % ofPIBSA in the binary blend had only a minimal effect on the shear rate ofthe nylon. As the amount of PIBSA is increased, the shear viscosityversus the shear rate is reduced, indicating there will be a desirablelowering of the viscosity of the thermoplastic mixture by inclusion ofthe AFO to the thermoplastic during mixing of the DVA. Additionally, asseen in the Table above, the use of the AFO results in only a minimalchange in the melt temperature of the polyamide.

The AFO, preferably succinic anhydride functionalized oligomers of lowmolecular weight, are present in the DVA in amounts ranging from aminimum amount of about 2 phr, 5 phr, 8 phr, or 10 phr to a maximumamount of 12 phr, 15 phr, 20 phr, 25 phr, or 30 phr. The range ofanhydride may range from any of the above stated minimums to any of theabove stated maximums, and the amount of anhydride may fall within anyof the ranges.

The invention, accordingly, provides the following embodiments:

-   A. A dynamically vulcanized alloy comprising at least one    isobutylene-containing elastomer; at least one thermoplastic resin,    and an anhydride functionalized oligomer, wherein sulfonamide    compounds are substantially absent from the alloy and wherein the    elastomer is present as a dispersed phase of small highly vulcanized    or partially vulcanized particles in a continuous phase of the    thermoplastic resin;-   B. The alloy of embodiment A, wherein the oligomer is selected from    the group consisting of an alkyl, an aryl, and an alkenyl oligomer;-   C. The alloy of embodiment A or B, wherein the oligomer has a    molecular weight in the range of 500 to 2500;-   D. The alloy of any preceding embodiment A to C or any combination    thereof, wherein the anhydride functionality in the oligomer is    either succinic anhydride or maleic anhydride;-   E. The alloy of any preceding embodiment A to D or any combination    thereof, wherein the anhydride functionalized oligomer is a    poly-n-alkyl succinic anhydride or a poly-iso-alkyl succcinic    anhydride;-   F. The alloy of any preceding embodiment A to E or any combination    thereof, wherein the functionalized oligomer is selected from the    group consisting of poly-isobutylene succinic anhydride,    polyisobutene succinic anhydride, polybutene succinic anhydride,    polyisopentene succinic anhydride, polypentene succinic anhydride,    polyoctenyl succinic anhydride, polyisooctenyl succinic anhydride,    poly-hexenyl succinic anhydride, and poly-dodecenyl succinic    anhydride;-   G. The alloy of any preceding embodiment A to F or any combination    thereof, wherein the alloy comprises 2 to 30 phr of the anhydride    functionalized oligomer, based on the amount of the    isobutylene-containing elastomer in the alloy;-   H. The alloy of any preceding embodiment A to G or any combination    thereof, wherein the thermoplastic resin in the alloy has a relative    viscosity, as measured per ASTM D 2857, of not more than 3.0;-   I. The alloy of any preceding embodiment A to H or any combination    thereof, wherein the at least one thermoplastic resin is a mixture    of at least two thermoplastic resins wherein the mixture has a    relative viscosity of in the range of 3.9 to 2.9;-   J. The alloy of embodiment I, wherein the thermoplastic resin    mixture is a mixture of a thermoplastic resin copolymer and a    thermoplastic resin homopolymer;-   K. The alloy of embodiment J, wherein the thermoplastic resin    homopolymer has a relative viscosity less than the relative    viscosity of the thermoplastic resin copolymer;-   L. The alloy of embodiment J or K, wherein the thermoplastic resin    homopolymer has a relative viscosity value in the range of 3.3 to    2.0;-   M. The alloy of any preceding embodiment A to L or any combination    thereof, wherein said elastomer is a halogenated butyl rubber;-   N. The alloy of any preceding embodiment A to M or any combination    thereof, wherein said elastomer is a copolymer of isobutylene and an    alkylstyrene;-   O. The alloy of any preceding embodiment A to N or any combination    thereof, wherein said elastomer is a copolymer of isobutylene and    paramethylstyrene, and is optionally halogenated;-   P. The alloy of any preceding embodiment A to O or any combination    thereof, wherein the thermoplastic resin is selected from the group    consisting of polyamides, polyimides, polycarbonates, polyesters,    polysulfones, polylactones, polyacetals,    acrylonitrile-butadiene-styrene resins, polyphenyleneoxide,    polyphenylene sulfide, polystyrene, styrene-acrylonitrile resins,    styrene maleic anhydride resins, aromatic polyketones, ethylene    vinyl acetates, ethylene vinyl alcohols, and mixtures thereof;-   Q. The alloy of any preceding embodiment A to P or any combination    thereof, wherein the thermoplastic resin is derived from at least    one amine;-   R. The alloy of any preceding embodiment A to Q or any combination    thereof, wherein the elastomer is present in the alloy in an amount    in the range of 55 to 90 weight percent;-   S. The alloy of any preceding embodiment A to R or any combination    thereof, wherein wherein the elastomer is a halogenated polymer of    isobutylene and paramethylstyrene derived units, wherein the polymer    comprises 7 to 12 wt % of the paramethylstyrene derived units;-   T. The alloy of any preceding embodiment A to S or any combination    thereof, wherein wherein the elastomer comprises 1.0 to 1.5 mol % of    a halogen;-   U. The alloy of any preceding embodiment A to T or any combination    thereof, wherein wherein the alloy comprises 8 to 12 phr of the    anhydride functionalized oligomer; and-   V. The alloy of any preceding embodiment A to U or any combination    thereof, wherein wherein the alloy comprises 2 to 6 phr of at least    one curative.

Examples

Test methods are summarized in Table 3.

When possible, standard ASTM tests were used to determine the DVAphysical properties (see Table 2). Stress/strain properties (tensilestrength, elongation at break, modulus values, energy to break) weremeasured at room temperature using an Instron™ 4204. Tensilemeasurements were done at ambient temperature on specimens (dog-boneshaped) width of 0.16 inches (0.41 cm) and a length of 0.75 inches (1.91cm) length (between two tabs) were used. The thickness of the specimensvaried and was measured manually by A Mahr Federal Inc. thickness gauge.The specimens were pulled at a crosshead speed of 20 inches/min. (51cm/min.) and the stress/strain data was recorded. The averagestress/strain value of at least three specimens is reported. Shore Ahardness was measured at room temperature by using a Zwick Durometerafter 15 seconds indentation. LCR viscosity was measured with a Dynisco™capillary rheometer at 30/1 L/D (length/diameter) at 220° C. at 300 l/s.The melting point was measured by differential scanning calorimetry at10°/minute.

Oxygen permeability was measured using a MOCON OxTran Model 2/61operating under the principal of dynamic measurement of oxygen transportthrough a thin film. The units of measure are cc-mil/m2-day-mmHg and thevalue obtained may be alternatively referred to as the permeability orimpermeability coefficient. Generally, the method is as follows: flatfilm is clamped into diffusion cells of the MOCON measuring unit; thediffusion cells are purged of residual oxygen using an oxygen freecarrier gas. The carrier gas is routed to a sensor until a stable zerovalue is established. Pure oxygen or air is then introduced into theoutside of the chamber of the diffusion cells. The oxygen diffusingthrough the film to the inside chamber is conveyed to a sensor whichmeasures the oxygen diffusion rate.

The extrusion surface smoothness (ESR) of a DVA is a measure of thesurface smoothness of the DVA, with lower numbers indicating a smoothersurface. The ESR is measured using a Surfanalizer, supplied by Federal,and measured in accordance with the manufacturer's instructions foroperation. Lower numbers are also indicative of the elastomer phasebeing more uniformly and well-dispersed within the continuousthermoplastic resin phase.

The percent bound nylon, also referred to as percent insoluble nylon, isthe amount of nylon that has reacted with the rubber to form a graftcopolymer which is insoluble in a solvent such as trifluoroethanol. Thepercent bound nylon was determined gravimetrically after twenty-fourhours Soxhlet extraction of the DVA with trifluoroethanol solvent toremove the soluble nylon, followed by forty-eight hours drying of thesolid residue in vacuum at 80° C. The bound or insoluble nylon iscalculated by subtraction of the soluble fraction from the total nylonin the DVA composition.

The fatigue life, also referred to as low temperature fatigue (LTF), isdetermined as follows: specimens are cut out using a JIS #3 die and from1 mm thick extruded cast film of the DVA, with a total of ten specimensare tested at one time for each sample set; using a Constant LoadDisplacement/Strain Fatigue Tester manufactured by Ueshima SeisakushoCo., at −35° C. and 5 Hz frequency, and a total displacement of 40% foreach specimen, the specimen is flexed as the cycle number is record; thetest is terminated when the specimens are broken.

TABLE 3 Parameter Units Test Physical Properties, injection moldedplaques Hardness Shore A ASTM D2240 Shore D ASTM D2240 Modulus 10%, 50%,100% MPa ASTM D412 Tensile Strength MPa ASTM D412 Elongation at Break %ASTM D412 LCR Viscosity Pa · s 30/1 L/D at 220° C. at 300 1/s MeltingPoint ° C. Differential Scanning Calorimetry at 10° C./minute MOCON (at60° C.) cc-mm/m²- day-mmHg

Samples were prepared of both comparative DVAs and exemplary DVAs madein accordance with the present invention. The components used in thesamples are identified in Table 4 below. The PIBSA form for the practiceof this invention is not restricted to the examples used and othercommercial offerings which are either neat or diluted in oil may also beemployed, especially if the molecular weight of the starting PIBSArenders it too viscous. The PIBSAs may also be heated so they can beeasily dispensed in mixing equipment and also to facilitate theirincorporation and mixing.

TABLE 4 Component Brief Description Commercial Source BIMSM 1 Brominatedpara-methylstyrene- isobutylene copolymer, 5 wt % PMS, 0.75 mol % BrPMS,Mooney viscosity, ML (1 + 8) 125° C. = 45 BIMSM 2 Brominatedpara-methylstyrene- isobutylene copolymer, 5 wt % PMS, 0.5 mol % BrPMS,Mooney viscosity, ML (1 + 8) 125° C. = 45 BIMSM 3 Brominatedpara-methylstyrene- isobutylene copolymer, 7 wt % PMS, 1.2 mol % BrPMS,Mooney viscosity, ML (1 + 8) 125° C. = 45 Polyamide Nylon 6/66, seeTable 1 for properties UBE 5024, from UBE copolymer 1 Chemical PolyamideNylon 6/66, see Table 1 for properties Ultramid^(R) C33 01 fromcopolymer 2 BASF Polyamide Nylon 6/66, see Table 1 for propertiesUltramid^(R) C31 01 from copolymer 3 BASF Polyamide Nylon 6, see Table 1for properties Ultramid B27 homopolymer 1 Polyamide Nylon 6, see Table 1for properties Ultramid B26 HM01 homopolymer 2 CompatibilizerEthylene-acrylic ester-maleic anhydride Lotader 4720 from terpolymer(EEA) Arkema Inc. PIBSA Polyisobutylene succinic anhydride, MW PIBSA 950from Texas before anhydride reaction = 950, viscosity Petrochemicals LPat 100° C. = 459 cSt, saponification # = 100 mg Or KOH/gm DovermulseH1000 from Dover Chemical Corp. Plasticizer n-butylbenzene sulfonamide(BBSA) Uniplex ™ 214, Uniplex Chemical

The DVA formulations are all set forth in the following tables. The DVAswere all prepared in the same manner, using a twin screw extruder mixer.Both comparative and exemplary DVA samples were tested to determine thephysical characteristics. The test results are also set forth below inthe following table.

The type of stabilizer used was identical for all composition and waspresent in the amount of 0.48 phr for all compositions. Two differentcurative packages were used. The first curative package, label as C1 inthe tables below, consisted of 0.15 phr zinc oxide, 0.30 phr zincstearate, and 0.65 stearic acid for a total additive amount of 1.58 phr.The second curative package, labeled as C2 in the tables below,consisted of 2.0 phr zinc oxide. For each example identified below, theDVA was prepared in the same manner, using the twin screw extruder.

TABLE 5 All parts are in phr Comp 1 Comp 2 1 2 3 4 5 BIMSM 1 100.0 100.0100.0 100.0 100.0 100.0 100.0 Talc 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Polyamidecopolymer 1 63 63 56 56 56 60 56 Polyamide homopolymer 1 0 0 14 14 14 1514 Compatibilizer 10 10 — 10 — — — PIBSA — — 10 10 10 10 10 BBSAPlasticizer 27 27 0 0 0 0 0 Cure Package C1 C1 C1 C1 C2 C2 C2 TestResults Melt Temperature, ° C. 176 176 210 211 210 206 208 Shore AHardness 85 85 95 92 92 96 95 100% modulus, MPa 5.91 5.36 9.77 7.8310.59 11.31 11.06 ultimate tensile strength, 15.88 13.59 12.44 8.7113.43 13.73 13.64 MPa Elongation at Break, % 416 390 223 160 203 209 206LCR Viscosity (Pa-s) @ Not 711 1120 940 1386 1323 1470 300 (1/s) @220°C., (L/D measured 30/1) MOCON at 60° C. 0.11 0.11 0.23 0.34 0.22 0.220.27

For samples 1 to 3 and 5, the total amount of thermoplastic resin is 70phr with sample 4 having a total amount of thermoplastic resin is 75phr. All the samples have an 80/20 ratio between the medium relativeviscosity thermoplastic resin and the low relative viscositythermoplastic resin. With the exemplary resins used in these samples,the mixture has a relative viscosity of approximately 3.26 and thus themixture has a relative viscosity classification of intermediate, and iswithin the desired range for the invention of not more than 3.9.

For samples 1 to 5, the melt temperature, Shore A hardness, and 100%modulus values increased due to the removal of the sulfonamidecontaining plasticizer and the inclusion of the AFO. As already noted,the increase in these values is deemed to actually be beneficial to thealloy to assist in further downstream processing and shaping of thealloy. The MOCON permeability coefficient is also increased over thecomparative compositions, but is within the desired range of less than0.65. For sample 2, when the compatibilizer is added to the mixture, theMOCON value increases relative to when it is absent in the AFOcontaining compounds.

A second set of samples were prepared, wherein the total amount ofthermoplastic resin was increased to 90 phr for each sample, with an80/20 ratio maintained between the two thermoplastic resins, and theamount of AFO, using exemplary PIBSA, was gradually increased todetermine the effect. The composition and test results are set forth inTable 6 below. For examples 6 to 10, cure package C2 was used.

TABLE 6 All parts are in phr 6 7 8 9 10 BIMSM 1 100.0 100.0 100.0 100.0100.0 Talc 2.5 2.5 2.5 2.5 2.5 Polyamide copolymer 1 72 72 72 72 72Polyamide homopolymer 1 18 18 18 18 18 Compatibilizer 0 0 0 0 0 PIBSA 1012.5 15 17.5 20 BBSA Plasticizer 0 0 0 0 0 Test Results MeltTemperature, ° C. 210 209 210 210 209 Shore D/A Hardness 48D 47D 46D 43D98A 100% modulus, MPa 13.61 13.66 12.99 12.43 11.82 Ultimate tensilestrength, 15.40 15.08 14.35 14.06 12.82 MPa Elongation at Break, % 214193 186 187 169 LCR Viscosity (Pa-s) @ 1412 820 965 1579 1180 300 (1/s)@220° C., (L/D 30/1) MOCON at 60° C. 0.096 0.096 0.125 0.173 0.175Fatigue Life at −30° C. (kc) 210 314 210 — 271

It should be noted that the Shore Hardness values for samples 6 to 9 areShore D values, versus the Shore A hardness values reported for samples1 to 5 and 10. It is known in the art that the Shore A scale is used for‘softer’ rubbers while the Shore D scale is used for ‘harder’ rubbers.Shore A and Shore D values do not correlate well, but for a givenelastomeric compound, the Shore A value will typically be higher thanthe Shore D value, and elastomeric compounds having Shore A values inthe range of 80 to 90 typically correspond to having Shore D values inthe range of about 28 to about 37. All of the sample compounds haveShore hardness values greater than the control compounds.

Also evident from the data in the Table 6 is that the DVA has a highermelt temperature (Tc). The higher Tc can be used to advantage insubsequent processing operations such as film blowing and tire moldingsince a faster solidification at higher temperature enables reduction ofcycle times.

The inclusion of an AFO in the DVA in place of the non-graftingsulfonamide compounds, in combination with a lower viscositythermoplastic, is a suitable plasticizer and viscosity modifier for theDVA. Additionally, the AFO does not negatively impact the melttemperature of the DVA, and thus is beneficial in film processing of theDVA and any downstream use of the film in finished curable articles suchas tires and hoses.

As the DVAs of the invention will be used as an air barrier layer, theimpermeability characteristics are also important, and should bemaintained at favorable values when seeking the desired morphology ofthe elastomer and thermoplastic resin. Additional samples were preparedto further improve the impermeability characteristics of the material.These compositions and properties are set forth in Table 7 below

TABLE 7 All parts are in phr 11 12 13 14 BIMSM 1 100.0 BIMSM 2 100 BIMSM3 100 100 Talc 2.5 2.5 2.5 2.5 Polyamide copolymer 1 56 56 56 Polyamidecopolymer 2 56 Polyamide homopolymer 1 14 14 14 Polyamide homopolymer 214 PIBSA 10 10 10 10 Zinc Oxide 2 2 2 2 Test Results Bound Nylon, % 6.463.52 5.96 7.78 ESR 61 66 24 29 LCR Viscosity (Pa-s) @ 1240 877 1219 1230300(1/s) @220° C., (L/D 30/1) MOCON at 60° C. 0.27 0.28 0.16 0.10

Torque versus time was measured for the elastomer used in samples 11 to13 to show the cure properties of the elastomer, see FIG. 2. As seen inFIG. 2, for BIMSM 3 once cure has begun, the time to reach ‘fully’ curedis approximately one minute (‘fully’ cured being indicated by therelatively horizontal line on the graph) and has a higher degree of curethan the other two samples. This increased degree of cure assists inensuring that alloy is fully cured when it exits the manufacturing line.While BIMSM 3 does not have more bound nylon than BIMSM 1 and 2, it doeshave a lower ESR and an improved impermeability coefficient. As theelastomer is the only material being cured when the DVS is mixed, thetorque versus time properties of the elastomer alone, as presented inFIG. 2, is indicative of how cure is progressing in an extruder duringDVA synthesis.

In comparing sample 13 to sample 14, the impermeability coefficient ofthe alloy is reduced by 25% by the use of a polyamide homopolymer havinga lower relative viscosity.

Further samples were prepared to determine the effect of varying thecure additive in the PIBSA extended compound. The composition and dataare set forth below in Table 8.

TABLE 8 All parts are in phr 15 16 17 18 19 20 21 BIMSM 1 100 100 100100 100 100 100 Talc 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Polyamide copolymer 156 56 56 56 60 60 60 Polyamide homopolymer 2 14 14 14 14 15 15 15 PIBSA10 10 10 10 10 10 10 Zinc Oxide 1 2 4 6 1 2 4 Test Results MOCON at 60°C. 0.209 0.19 0.174 0.175 0.178 0.16 0.148 LTF (1,000 cycles) 30 — 302310 66 — 250

As seen in the data of Table 8, an increase in the amount of curativedecreases the MOCON permeability coefficient while favorably alsoincreasing the LTF values.

DVAs in accordance with the present invention have a MOCON permeabilitycoefficient, measured at 60° C., of not more than 0.65cc-mm/m²-day-mmHg, preferably not more than 0.50 cc-mm/m²-day-mmHg, orpreferably not more than 0.30 cc-mm/m²-day-mmHg. In any of theembodiments of the invention, the MOCON permeability coefficient,measured at 60° C., is not more than 0.20 cc-mm/m²-day-mmHg, and ispreferably in the range of 0.30 to 0.10. As evident from the data above,the compositions of the present invention have a very low permeabilitycoefficient, well within the desired range for an air barrier material.

The inventive compositions can be used to make any number of articles.In one embodiment, the article is selected from tire curing bladders,tire innerliners, tire innertubes, and air sleeves. In anotherembodiment, the article is a hose or a hose component in multilayerhoses, such as those that contain polyamide as one of the componentlayers. Other useful goods that can be made using compositions of theinvention include air spring bladders, seals, molded goods, cablehousing, and other articles disclosed in THE VANDERBILT RUBBER HANDBOOK,P 637-772 (Ohm, ed., R.T. Vanderbilt Company, Inc. 1990).

What is claimed is:
 1. A dynamically vulcanized alloy comprising: a) atleast one elastomer derived from 1) at least one C₄ to C₇ isoolefinmonomer and 2) at least one multiolefin or other polymerizable monomer;b) at least one polyamide having a relative viscosity in the range of2.9 to 3.9 per ASTM D2857; c) at least one polyamide having a relativeviscosity below 2.9 per ASTM D2857; and d) a viscosity modifier of 10 to30 phr of an anhydride functionalized oligomer grafted to at least oneof the polyamides, wherein the oligomer, prior to anhydridefunctionalization, is a viscous liquid having a molecular weight in therange of 500 to 2500, wherein the polyamides form a polyamide mixture,the dynamically vulcanized alloy has less than 100 ppm by weight ofsulfonamides and the elastomer is present as a dispersed phase of smallvulcanized or partially vulcanized particles in a continuous phase ofthe polyamide mixture.
 2. The alloy of claim 1, wherein the oligomer isselected from the group consisting of an alkyl derived oligomer, an arylderived oligomer, and an alkenyl derived oligomer.
 3. The alloy of claim1, wherein the anhydride functionality is either a succinic anhydride ora maleic anhydride.
 4. The alloy of claim 1, wherein the functionalizedoligomer is selected from the group consisting of poly-isobutylenesuccinic anhydride, polyisobutene succinic anhydride, polybutenesuccinic anhydride, polyisopentene succinic anhydride, polypentenesuccinic anhydride, polyoctenyl succinic anhydride, polyisooctenylsuccinic anhydride, poly-hexenyl succinic anhydride, and poly-dodecenylsuccinic anhydride.
 5. The alloy of claim 1, wherein the 1) at least oneisoolefin monomer is isobutylene, isobutene, 2-methyl-1-butene,3-methyl-1-butene, 2-methyl-2-butene, 1-butene, 2-butene, hexene, or4-methyl-1-pentene and 2) at least one multiolefin or otherpolymerizable monomer is isoprene, butadiene,2,3-dimethyl-1,3-butadiene, myrcene, 6,6-dimethyl-fulvene, hexadiene,cyclopentadiene, piperylene, styrene, or dichlorostyrene.
 6. The alloyof claim 1, wherein the elastomer is functionalized with a halogen,acid, or ester.
 7. The alloy of claim 1, wherein the elastomer ispresent in the alloy in an amount in the range of 55 to 90 weightpercent based on the amount of elastomer and polyamides in the alloy. 8.The alloy of claim 1, wherein the elastomer comprises 1.0 to 1.5 mol %of a halogen.
 9. The alloy of claim 1, wherein the polyamide having arelative viscosity of below 2.9 is 5 to 25% of the total polyamide inthe system.
 10. The alloy of claim 1, wherein the alloy comprises a curesystem of at least one curative and optional cure accelerators.
 11. Aprocess of preparing a dynamically vulcanized alloy, the processcomprising the following steps: a) selecting at least one elastomerderived from 1) at least one C₄ to C₇ isoolefin monomer and 2) at leastone multiolefin or other polymerizable monomer; b) selecting at leastone polyamide having a relative viscosity in the range of 2.9 to 3.9 perASTM D2857 and at least one polyamide having a relative viscosity below2.9 per ASTM D2857; and c) selecting a viscosity modifier of ananhydride functionalized oligomer, wherein the oligomer, prior toanhydride functionalization, is a viscous liquid having a molecularweight in the range of 500 to 2500, d) mixing in a mixer the at leastone elastomer, the polyamides, and the viscosity modifier together untilthe polyamides have melted and the anhydride functionalized oligomer isgrafted to at least one of the polyamides to form a mixed melted blend,e) adding a cure package of at least one curative into the mixer, f)continuing to mix the blend under conditions of high shear and elevatedtemperature to vulcanize the elastomer and disperse the vulcanizedelastomer as discrete particles in a polyamide matrix of the polyamides;and g) obtaining a dynamically vulcanized alloy wherein during step d),the viscosity modifier is added to the mixer simultaneously with atleast one of the polyamides or after the polyamides begin to melt in theextruder and the viscosity of the combined polyamide and viscositymodifier is lower than the viscosity of the at least one elastomer. 12.The process of claim 11 wherein the cure package is added to the mixerafter the polyamides have melted and mixed with the elastomer.
 13. Theprocess of claim 12 wherein the cure package comprises a metal oxide.14. The process of claim 11 wherein the cure package comprises a metaloxide.
 15. The process of claim 11 wherein the at least one polyamidehaving a relative viscosity below 2.9 is a homopolymer.
 16. A method ofincreasing the melt temperature of a dynamically vulcanized alloy,wherein the dynamically vulcanized alloy comprises a) at least oneelastomer derived from 1) at least one C₄ to C₇ isoolefin monomer and 2)at least one multiolefin or other polymerizable monomer; b) at least onepolyamide having a relative viscosity in the range of 2.9 to 3.9 perASTM D2857 and a defined melt temperature; and c) 2 to 30 phr of ananhydride functionalized oligomer, wherein the oligomer, prior toanhydride functionalization, has a molecular weight in the range of 500to 2500, the method also comprising replacing a portion of the at leastone polyamide with a polyamide homopolymer having a relative higher melttemperature.
 17. The method of claim 16 wherein the polyamide having arelative higher melt temperature is 5 to 25% of the total polyamide inthe dynamically vulcanized alloy.